In 2008, by pyrosequencing of cDNA from the brains of several parrots suffering from Proventricular Dilatation Disease

Proventricular Dilatation Disease

Proventricular Dilatation Disease is a disease affecting psittacines . It was first recognized and described in 1978 by Dr. Hannis L. Stoddard...

 (PDD), Honkavouri et al. identified the presence of a novel Borna virus .

Process of Discovery

Using real time PCR, the investigators confirmed the presence of this virus

Virus

A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...

 in the brains and proventriculus

Proventriculus

The proventriculus is part of the digestive system of birds, invertebrates and insects.-Birds:The proventriculus is a standard part of avian anatomy...

 of three cases of PDD but not in four unaffected birds. At approximately the same time, Kistler and her colleagues used a microarray

Microarray

A microarray is a multiplex lab-on-a-chip. It is a 2D array on a solid substrate that assays large amounts of biological material using high-throughput screening methods.Types of microarrays include:...

 approach to identify a Borna virus hybridization signature in three out of five PDD cases but not in eight control parrots .

Recovery and Naming

Using high-throughput pyrosequencing in combination with conventional PCR cloning

Cloning

Cloning in biology is the process of producing similar populations of genetically identical individuals that occurs in nature when organisms such as bacteria, insects or plants reproduce asexually. Cloning in biotechnology refers to processes used to create copies of DNA fragments , cells , or...

 and sequencing, these investigators recovered the complete viral genome sequence and named this virus Avian Borna Virus (ABV). At least seven distinct ABV genotypes have now been identified and sequenced. In general these ABV genotypes show only about 65% sequence identity with mammalian Borna disease

Borna disease

Borna disease is an infectious neurological syndrome of warm-blooded animals, caused by Borna disease virus, which causes abnormal behaviour and fatality....

 Virus (BDV).

Structure

The overall structure of the bornaviral genome is well conserved. Thus the number and order of genes is unchanged as is the structure of [Transcription (genetics)|transcription]] initiation and termination sites. Rinder and her colleagues have shown that ABV apparently lacks a 22-nucleotide

Nucleotide

Nucleotides are molecules that, when joined together, make up the structural units of RNA and DNA. In addition, nucleotides participate in cellular signaling , and are incorporated into important cofactors of enzymatic reactions...

 fragment that serves a regulatory function for the genes coding for viral proteins X and P .

Further Research

Cultured ABV has been shown to induce typical PDD in Patagonian conures (Cyanoliseus patagonus) with a typical interval of 55–60 days between infection and death . Gancz and his colleagues showed that inoculation of ABV4-infected brain tissue will also induce typical disease in cockatiels (Nymphicus hollandicus) after 60–95 days. Ongoing studies suggest that the virus is spread by the fecal-oral route but it is also possible that respiratory and vertical spread also occur.